Oscillation-detector.



G. E. RUSSELL. OSGILLATION DETECTOR. APPLICATION FILED SEPT. 4, 190a.

Patented Sept. 22, 1908. 2 SHEBTSSHEET 1.

U. B. RUSSELL. OSCILLATION DETECTOR. APPLIQATION FILED SEPT.4,1906.

Patented Sept. 22, 1908.

2 SHEETS-SHEET 2.

Fig- 5- UNITED STATES PATENT OFFICE.

CHARLES E. RUSSELL, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO STONE TELEGRAPH AND TELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS.

Specification of Letters Patent.

Patented Sept. 22, 1908.

Application filed September 4, 1906. Serial No. 333,041.

Tocll whom it may concern:

Be it known that I, CHARLES E. R ssELL, a citizen of the United States, and a resident of Cambridge, in the county of MiddleseX and State of Massachusetts, have invented a new .form a part of this specification and which illustrate one form of magnetic detector embodying the principles of my invention, although it is to be understood that I do not limit myself to the particular embodiment thereof which is illustrated in said drawings, inasmuch as many modifications may be made therein without departing from said principles.

In the drawings Figure 1 is a diagram illustrating my invention in its simplest form. Fig. 2 is a front elevation partly in section of a practical embodiment of my invention. Fig. 3 is a section taken on the line 33 of Fig. 2. Fig. 4 is a diagram showing a set of curves drawn to rectangular coordinates in which the ordinates represent magnetic induction and the abscissae represent magnetomotive force.

In the drawings, V represents an elevated conductor including the primary I of a trans former, the secondary of which I is serially included in a resonant receiving circuit which contains the condenser C, the coil L and the solenoids 2, 2 which may consist of a few turns of stranded wire.

'1 represents a permanent magnet which forms a practically closed magnetic circuit and to w ich the soft iron cores 2 are magnetically connected.

3 represents a movable magnetizable member forming art of the magnetic circuitcomprised by t e permanent magnet 1, and which may be a diaphragm similar to those employed in magneto telephones. A carbon button6 may be secured to the center of saiddiaiohragm so as to form a variable contact with the pin 4 which is electrically connected with the magnet 1 and which may be adjusted by means of the milled head 5. Al

thoughnot absolutely essential to operativeness, I prefer to employ an adjustable permanent magnet 7 arranged as shown for the pur ose of balancing the normal pull'exerted on t e diaphragm 3 by the magnetic flux existing in the magnets 1, 2.

R- is a resistance and B is a battery, the resistance and battery constituting a potentiometer for adjusting the electromotive force impressed on the circuit including the telephone T, the diaphragm 3, the carbonbutton 6 and the pin 4.

The operation of my invention may be understood by having reference to Fig. 4. In

Fig. 4 curve (1) represents the variation with cyclically varying magnetomotive force H of the magnetic flux B in a magnetic circuit,

and 'curve (2) represents the variation with progressively increasing positive magnetomotive force H of the magnetic flux B in a magnetic circuit when the magn'etic'member upon which said magnetomotive force is impressed is surrounded by a solenoid through which high frequency electrical oscillations are passing. It will be noted that the ordinates of curve (2) are greater for a given magnetomotive force than the ordinates of that part of curve (1) comprised between H=O and H=a, when H is increasing, on account of the increase of the permeability of the magnetic member which is effected by the passage of the high frequency oscillations around the solenoid inclosing said member.

In the normal condition of the apparatus, the magnitude of the magnetic flux in the cores 2, which preferably are magnetically saturated, is represented by the ordinate a b. When the oscillations to be detected pass through the solenoids 2, 2, the resulting increase in the permeability of the cores 2 or, in other'words, the resulting decrease in the magnetic reluctance of said cores, results in a greater magnetic flux in the magnetic circuit of-which said cores form a part. This increase in magnetic flux is represented by the difference between the ordinates a b and a 0, namely, b c, and results in a slight movement of the referably balanced diaphragm 3 toward t e cores 2. Said movement of the diaphragm results in a variation of the resistance of the contact formed by the carbon button 6 with the pin 4 and therefore produces a variation in the current flowing in the circuit of the telephone T, whereby the signal to be received is made manifest to the receiving operator.

When the oscillations cease to flow in the circuit of the solenoids 2, 2, the permeability of the cores 2 recedes to its normal value, indicated in Fig. 4 by the ordinate a b, so that it will be seen that my oscillation detector is of the self-restoring type.

Although l have shown my oscillation detector associated with an elevated conductor by means oi" a resonant circuit inductively related to said elevated conductor, it is to be. understood that said detector may be associated with a receiving conductor in any manner which suitable for the purpose.

Referring to the practical embodiment of my invention which 1 have illustrated in Fig. 2 for thepurpose of more fully disclosing-the same, Hi represents a base plate which may be of wood and which may rest upon a sheet of fell. 17 or other vibration-absorbing material. 'lhe magnet 1 is shown as secured to the base 16 by the screws 14-, 14, through the former of which electrical connection is made between the battery B and the permanent magnet l and thence by the pin 4 to the carbon button 6 and diaphragm-support S, which is secured to the base by the screw 1.5, electrically connected through the telephone T to said battery. The diaphragm 3 may be held by the springs ll, 11 in a recess cut into the support 8. A frame 9 may be bolted to the support 8 and to said frame the balancing magnet 7 may be adjustably supported by the nuts 10. Better results are obtained if the oscillation detector ineloscd in a bell jar 20 secured in any suitable manner to the base 16 and evacuated by suitable apparatus connected with the outlet 18 and provided with a valve 15).

I claim:

1. An oscillatimi detector comprising a m'agnetizable member forming part of a magnetic circuit, a source of constant unidirectional magnetomotive force associated with and forming part of an oscillation circuit, a

permanent magnet in fixed relation with respect to said core, a diaphragm actuated by the increase in the magnetic flux in said core resulting from the passage of the electrical oscillations to be detected through said coil, an electric circuit including a signal-indicating device and a source of electromotive force, and means whereby current variations may be. created in said electric circuit by the -1novement of said diaphragm. i

3; An oscillation detector comprising a soft iron core, -a coil surrounding said core and forming part of an oscillation-circuit.a permanent magnet in iixed relation with respect to said core, a balanced diaphragm actuated bythe increase in the magnetic flux in said core resulting from the passage of the electrical oscillations to be detected through said coil, an electric circuit including a signal-indicating device and a source of electromotive force, and means whereby current variations may be created in said electric circuit by the movement of said diaphragm.

In testimony whereof, I have hereunto subscribed my name this 24th day of July CHARLES E. RUSSELL.

Witnesses G. A. HIGGINS, GEo. K. WooDwoRTn. 

